2.0 Analysis 2.1 Fairchild Metro III (BLS 404) - Flight Planning The Fairchild Metro III (BLS 404) crew was within the allowable scheduling limits regarding their maximum duty day, and was within the limits for the maximum flying time for the previous 30- and 90-day time periods. Because the station stops during the day enabled the crew to recoup time lost to unforeseen delays, the crew was not required to rush their approaches to make up for lost time. The arrival controller was aware of the preferences of various aircraft crews, and tried to anticipate their needs. The arrival controller believed that, compared to some aircraft, the Fairchild Metro III aircraft type normally flies faster on approach and is able to maintain that approach speed until closer to the runway. He was, therefore, not initially alarmed when the Fairchild Metro III converged with the F-28. Faster, steeper approaches compress crew duties during the approach phase of flight into a shorter time, leaving less free time for the crew to scan the sky ahead for other traffic. 2.2 Fairchild Metro III (BLS 404) - Arrival and Traffic Identification Throughout the approach, the DC-9 (ACA 178) and the F-28 (TAF 1328) were difficult to identify because of their similar paint schemes and the urban background. Because the upper air winds created a slight crosswind from the left for the Fairchild Metro III as it was flying the base leg of the visual approach, the nose of the aircraft was oriented slightly into the wind, and to the left of the ground track observed by the arrival controller on radar. When the Fairchild Metro III crew received visual approach clearance, scattered to broken cloud existed in the vicinity of the airport at an altitude between that of the Fairchild Metro III and the F-28, and may have obscured the F-28 from view. Because the Fairchild Metro III crew members were not aware of the number of aircraft in sequence ahead of them when they received the clearance for the visual approach, they were not looking for more than one aircraft. The crew saw the DC-9 at their 11:30 position, where their traffic could be expected to appear. Both the F-28 and the DC-9 were probably too far away for reliable visual identification. Because the DC-9 and the F-28 are similar in appearance, the crew misidentified the DC-9 (ACA 178) as the F-28 (TAF 1328) and accepted the DC-9 as their assigned traffic to follow. As the Fairchild Metro III continued the approach, the distance between it and the DC-9 decreased, but the angle increased, so that the fuselage of the DC-9 probably never presented an image large enough for reliable visual identification. When the arrival controller advised the Fairchild Metro III crew of their aircraft's relative groundspeed, the crew saw no discrepancy, and simply acknowledged the call. By then, the F-28 may have been visually recognizable; however, because the F-28's position was about 55 degrees to the right (two o'clock position), the Fairchild Metro III crew did not see the F-28. Because a mental image of a situation, once formed, is very resistant to change, the Fairchild Metro III crew did not interpret the arrival controller's hint about the aircrafts' relative speed to mean that something was wrong with their assessment of the traffic pattern. It was only when they learned that the position of their actual preceding traffic was greatly different than they believed, that they were able to re-evaluate their situation. 2.3 Fairchild Metro III (BLS 404) - Tower After the Fairchild Metro III crew acknowledged the position of the F-28 and changed to Tower frequency, the airport controller conferred with the arrival controller about the crew's request to use runway 25. During the 20-second period in which the controllers were co-ordinating, the Fairchild Metro III was closing with the Cessna 152. By the time the Fairchild Metro III crew received the instruction to execute a 360-degree turn to the left to rejoin the approach to runway 31, the Metro was at a position such that separation between the two aircraft during the turn was reduced to 0.4 nm horizontal with no vertical separation. The airport controller had cleared the Cessna 414 (C-FSAL) to taxi to position and hold on runway 31 just before the first call to Tower from the Fairchild Metro III. The controller's attention was then directed to the approach area during the first ROC and the second ROC, and when the F-28 crew called Tower on short final, the airport controller was preoccupied with the first two incidents and did not issue the appropriate direction to the F-28. 2.4 Separation and Control The requirements of the inter-unit agreement were not met when control of the Fairchild Metro III (BLS 404) was transferred to Tower before its conflict with the F-28 (TAF 1328) was resolved. Because both the Fairchild Metro III and the F-28 were being flown on an IFR flight plan, the arrival controller was not required to provide a minimum of 2 nm separation between them, as required by the inter-unit agreement for VFR aircraft. Because the crews were carrying out visual approaches, terminal area IFR separation standards also did not apply to them as the crew would maintain visual separation from the aircraft they were following. Separation between IFR aircraft in the vicinity of an airport during visual approaches can therefore decrease below the 2 nm standard applicable to VFR aircraft without any requirement on the part of the approach controller to advise the crews or take other action. The arrival controller was reluctant to intervene because the Fairchild Metro III was cleared for a visual approach, and the crew was responsible for its own separation from other aircraft. 2.5 Visual Approach Procedures Arrival controllers are not required by MANOPS to provide traffic sequence numbers when issuing visual approach clearances. Given that the Fairchild Metro III crew saw only one aircraft on approach to runway 31, traffic sequence information might have led them to inquire about the other aircraft on approach, and more quickly acquire correct traffic information. 2.6 Tower Procedures The pilot of the Cessna 152 (C-FGEK) had, by prior arrangement with the airport controller, turned down the volume control on his radio. He was, therefore, unable to hear the controller's instruction to him, transmitted on the Tower 118.3 MHz frequency, to turn north. Although such an approval by Tower to turn down the volume momentarily conforms to airspace use regulations, handling the Cessna 152 on a discrete frequency, such as the 124.5 MHz frequency available in the Tower, would have allowed the pilot to make his traffic broadcasts while maintaining contact with Tower. 2.7 ACC Training and Staffing ATSAMM requires annual refresher training to be provided to all operational personnel; although no such training had been carried out at either the Tower or the ACC within the 12 months previous to the occurrences, it cannot be determined whether refresher training would have affected the controller's handling of the occurrence aircraft. Controller training regarding the limitations of human physiology in the visual identification and recognition of other aircraft is not currently provided. Such training might help controllers recognize situations in which aircraft crews have misidentified traffic from which visual separation must be maintained. Staffing at the ACC was less than the operational strength required by the Transport Canada guidelines. Because of the understaffing, controllers were required to work extra duty shifts to make up for the shortfall. However, it is difficult to assess precisely how much the arrival controller's increased recent workload may have affected his on-the-job efficiency. Because of the shortage of operational staff, Terminal supervisors were required to work operational shifts, and therefore stand-back supervision was not being provided in the Terminal specialty at the time of the occurrences. 3.0 Conclusions 3.1 Findings The scattered to broken cloud condition observed in the vicinity of the airport may have obscured the F-28 from the view of the crew of the Fairchild Metro III. The arrival controller did not provide the Fairchild Metro III crew with an approach sequence number, nor did the ATC MANOPS require that he do so. Approach sequence information might have helped the Fairchild Metro III crew to correctly recognize air traffic on approach to runway 31. When the Fairchild Metro III crew was initially advised of their traffic, the aircraft was probably too far away for a reliable visual identification. The similar configuration and paint schemes of the DC-9 (ACA 178) and the F-28 (TAF 1328) made them difficult to differentiate, especially against an urban background. The Fairchild Metro III's high speed on initial approach reduced the time available for the crew to scan for traffic. The crew's correction for the upper winds pointed the nose of the Fairchild Metro III slightly in the direction of the DC-9. The Fairchild Metro III crew misidentified the DC-9 (ACA 178) as the F-28 (TAF 1328). Because the Fairchild Metro III was on a visual approach and its crew was responsible for its own separation, the arrival controller was reluctant to intervene. The Fairchild Metro III approached within .7 nm horizontal and 500 feet vertical separation from the F-28 (TAF 1328) during the first ROC. The requirement of the Air Traffic Control inter-unit agreement, to resolve conflicts before aircraft handoffs, was not met. During the turn to rejoin final approach to runway 31, the Fairchild Metro III passed with 0.4 nm horizontal separation and no vertical separation from the Cessna 152 (C-FGEK). When the F-28 (TAF 1328) called Tower on short final approach, the airport controller was preoccupied and did not issue the appropriate direction. There is no separation standard other than visual separation for IFR aircraft on visual approaches. Terminal supervisors were required to work operational shifts; therefore, stand-back supervision was not being provided in the Terminal specialty. The arrival controller's workload may have decreased his on-the-job efficiency. Required annual refresher training for controllers had not been carried out at either the Tower or ACC within the 12 months before the occurrences. There is reportedly no controller training provided concerning the limitations of human physiology, and the limitations of pilots in identifying other airborne aircraft during visual approaches. The Cessna 152 (C-FGEK) pilot was not monitoring Tower frequency during the occurrences, with permission from the airport controller. 3.2 Causes The first risk of collision incident occurred because the Fairchild Metro III crew misidentified the preceding aircraft on approach. Contributing factors were the confusing visual cues in the approach environment, the lack of separation standards other than visual separation for IFR aircraft on visual approaches, and the arrival controller's reluctance to intervene. Possible contributing factors were the lack of an approach sequence number, the reduced staffing level at the Area Control Centre, and that annual refresher training for controllers had not been carried out.